1. Field of the Invention
The present invention relates to a covered endoscope system in which a coverable endoscope is sheathed with a cover and a body cavity is examined.
2. Description of the Related Art
In recent years, endoscopes have been widely adopted in the fields of industries and medicine alike.
As for endoscopes employed in the field of medicine, since an endoscope is inserted into a living body, a patient's body fluid or mucus sometimes adheres to an observation window formed at the distal part of an insertional part of the endoscope and thus reduces any possibility of a thorough observation of a lesion. An endoscope system is provided with an air supply function for supplying air to blow off remaining water from the observation window and a water supply function for supplying water to clean the observation window. The air or water supply function is activated by operating an operation button formed in the proximal portion of the endoscope, and executed via an air supply channel or a water supply channel.
The endoscope has multiple channels including not only the air and water supply channels but also a suction channel and a treatment adapter channel.
By the way, an endoscope that has been used for treatment must be cleaned or disinfected immediately, so that it can be reused for the next patient. However, it is a nuisance and time-consuming to thoroughly clean and disinfect an endoscope. This constitutes a factor in the deterioration of the use efficiency of an endoscope.
A covered endoscope has recently been employed, wherein an endoscope itself is sheathed with a cover, and used for each patient. The cover with which the endoscope is sheathed is disposed of after treatment is completed. This covered endoscope permits simple cleaning and disinfection.
In the covered endoscope, only channels which must open onto a patient's body cavity are mounted on a cover. A coverable endoscope having an observing means and an illuminating means is sheathed with a cover so as to not directly touch the inside of a patient's living body.
This kind of covered endoscope has been disclosed in, for example, U.S. Pat. No. 4,646,722 or U.S. Pat. No. 3,162,190.
In case a laser treatment adaptor is used in conjunction with a covered endoscope for treatment, when a laser beam generated by the laser treatment adaptor is irradiated to a region to be treated, part of the laser beam is reflected from the region to be treated, and enters an imaging device via an observation window and an observation optical system which are mounted in the distal part of an endoscope. This damages the imaging device either physically or optically. To avoid this damage, some endoscopes are provided with an optical filter that prevents a laser beam from passing through an objective optical system of an endoscope.
A laser beam currently employed for endoscopic treatment includes, for example, a YAG laser beam, a CO.sub.2 laser beam, and a KTP laser beam which have different wavelengths. A single kind of filter can cut off only a specific laser beam, which necessitates endoscopes having filters designed for respective laser beams. When an observational beam irradiated from an illumination optical system is likely to be reflected from a region to be treated and cause a halation, an endoscope having a polarizing filter must be used. Observation using infrared rays requires an endoscope having an infrared observation filter. Thus, an endoscope having a filter designed for a specific band of wavelengths or purpose of use of a beam must be employed depending on the nature of examination or treatment.
Aside from the foregoing endoscopes having various filters in the optical systems thereof, an endoscope having a streamlined hood at the distal part thereof, and an endoscope having a hood that projects by a specified distance to provide a distance between the distal part thereof and a region to be treated have been put to use.
Procuring multiple endoscopes in compliance with purposes of use has been a great financial burden to a user.
On the other hand, when a high-frequency treatment adaptor is inserted into a treatment adaptor channel of a cover and treatment is performed, a noise generated by the high-frequency treatment adaptor has an adverse effect on an imaging device placed inside the distal part of a coverable endoscope. Endoscopic images produced appear with noises on a monitor, which are, therefore, hard to see. As a countermeasure, the imaging device placed in the endoscope is provided with an electromagnetic shield. Nevertheless, it seems almost impossible to eliminate the noise perfectly.
An observation window formed at the distal part of a cover is shaped substantially like the distal part of a coverable endoscope. A patient's body fluid or mucus tends to adheres to the observation window, whenever the observation window is not dewatered soon after cleaned.
The layout of a coverable endoscope, a water supply channel, and an air supply channel, which run through a cover, has not been devised even though there have been many careful studies on the matter. Therefore, a field of view is disturbed, or the flow of fluid through fluid pipes or air pipes is disordered to eventually disrupt the air or water supply function.
Furthermore, when the observation window become cloudy, observation images appearing on the monitor become hard to see.
In the covered endoscope, an endoscope insertion channel into which a coverable endoscope is inserted is formed in an insertional part cover or one of the components of a cover. Nevertheless, a guide has not been formed in an endoscope insertion hole in a locking cap formed in the proximal portion of the insertional part cover or an inlet of an endoscope alignment hole formed at the distal part of the insertional part cover.
Therefore, when the coverable endoscope is inserted in the insertional part cover, the rigid distal part of the coverable endoscope is hooked on the locking cap or the inner circumferential surface of a distal structure. Thus, insertional smoothness is poor. When the coverable endoscope is pushed into the endoscope insertion channel forcibly, an insertional part of the coverable endoscope may be bent, an optical lens placed in the distal part of the coverable endoscope may be damaged, or the insertional part cover may be torn.
In the covered endoscope, the distal part of the coverable endoscope is fitted into the endoscope alignment hole, and thus aligned and secured. The diameter of the endoscope alignment hole is designed larger than necessary so that the distal part of the covered endoscope will be fitted into the endoscope alignment hole smoothly. Furthermore, the profile irregularity of the inner circumferential surface of the alignment hole is lowered much more than necessary so that the distal part of the coverable endoscope can be inserted into the endoscope alignment hole smoothly.
Consequently, only a low frictional resistance is present between the endoscope alignment hole and the distal part of the coverable endoscope. When endoscopic examination is conducted in this state, if bending is performed, the distal part of the coverable endoscope may sometimes be displaced from the endoscope alignment hole.